It is not known precisely where angels dwell whether in the air, the void, or the planets. It has not been God's pleasure that we should be informed of their abode. Voltaire
It is not known whether Martin ever completely accepted as a gentleman-scholar the Clay Tredgold who was devoted to everything about astronomy except studying it. Sinclair Lewis
These pictures are not occult, but they are psychic because everything that emanates from the human spirit or human brain is psychic. It is not supernatural; nothing is. It is preternatural in the sense that it is not known to our ordinary senses. Arthur Conan Doyle
This Duhamel has invented an infinity of machines which serve no purpose, has written and translated a multitude of books on agriculture, of which it is not known if they have any useful result, that is still awaited. Henri-Louis Duhamel du Monceau
On the third stage is used for medicine, it is not known to the public. Betty Hill